An investigational everolimus-eluting stent with a bioabsorbable polymer coating performed comparably to one with a durable coating, researchers found.

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In patients with symptomatic coronary artery disease, an investigational everolimus-eluting stent with a bioabsorbable polymer coating (Synergy) performed comparably to an everolimus-eluting stent with a durable polymer coating (Promus Element).

The newer stent was noninferior on the primary angiographic endpoint of in-stent late loss at six months.

An investigational everolimus-eluting stent with a bioabsorbable polymer coating performed comparably to one with a durable coating in patients with symptomatic coronary artery disease, a preliminary randomized trial showed.

The Synergy stent, whether delivering full or half doses of everolimus (Afinitor), was noninferior to the Promus Element stent for the primary clinical endpoint of target lesion failure or target lesion revascularization at 30 days, according to Ian Meredith, MBBS, PhD, of MonashHeart in Melbourne, Australia, and colleagues.

In addition, the newer stent was noninferior on the primary angiographic endpoint of in-stent late loss at six months, the researchers reported online in the Journal of the American College of Cardiology. The findings were originally reported at the Transcatheter Cardiovascular Therapeutics meeting last year.

They acknowledged that the findings were preliminary and said that a larger randomized trial is warranted.

Although the benefits of drug-eluting stents with durable polymer coatings have been well established versus bare-metal stents, the durable coating has been associated with hypersensitivity reactions, delayed healing, and incomplete endothelialization, which could increase the risk of late and very late stent thrombosis.

Practice guidelines recommend at least 12 months of dual antiplatelet therapy to mitigate the risk, but such a prolonged treatment raises concerns about bleeding, patient compliance, the need to interrupt treatment for invasive procedures, and higher costs.

One approach explored for reducing the risk of late thrombotic events with drug-eluting stents and, as a result, reducing the need for extended dual antiplatelet therapy is the use of bioabsorbable polymer coatings.

In the EVOLVE noninferiority trial, Meredith and colleagues compared two bioabsorbable polymer Synergy stents -- one delivering a full dose of everolimus (38 µg to 179 µg depending on stent length) and one delivering a half dose (19 µg to 90 µg depending on stent length) -- with the durable polymer Promus Element stent delivering a full dose of everolimus.

The trial was conducted at 29 sites in Europe, Australia, and New Zealand and included 291 patients with a de novo lesion of 28 mm or less in length, in a coronary artery with a diameter of 2.25 to 3.5 mm. The patients had stenosis of at least 50% but no coronary occlusion.

After stent placement, patients received 75 mg of clopidogrel (Plavix) daily for at least six months. Those who did not have a high risk of bleeding received it for at least a year.

The primary clinical endpoint of the trial was the 30-day rate of target lesion failure -- defined as cardiac death or myocardial infarction related to the target vessel -- or target lesion revascularization.

Target lesion failure occurred in none of the patients who received the Promus Element stent, one patient (1.1%) who received the full-dose Synergy stent, and three patients (3.1%) who received the half-dose Synergy stent. The differences between the groups were not statistically significant.

By six months, the rates were 3.1%, 2.2%, and 4.1% in the three groups, respectively, and still not significantly different from each other. Rates of other clinical events were low and comparable in all three groups. There were no cases of stent thrombosis through six months.

Similarly, the six-month in-stent late loss was not different between the three groups. It was 0.15 mm for the Promus Element stent, 0.10 mm for the full-dose Synergy stent, and 0.13 mm for the half-dose Synergy stent.

The differences between the Synergy stents and the Promus Element stent met criteria for noninferiority (P<0.001 for both).

Two angiographic measurements favored the half-dose Synergy stent over the Promus Element stent at six months -- in-stent minimum lumen diameter and in-segment percent diameter stenosis (P=0.02 for both) -- although the researchers noted that they could be chance findings.

Nevertheless, they wrote, "the angiographic outcomes of the EVOLVE study suggest that it may be possible to achieve at least comparable efficacy with a lower dose of everolimus than is used in commercially available everolimus-eluting stents."

The authors noted some limitations of the study, including the lack of power to detect differences in clinical outcomes, the relatively simple lesions included in the study, and the lack of information on whether using the bioabsorbable polymer coating reduces thrombotic events as well as the need for prolonged dual antiplatelet therapy.

Meredith has received honoraria from Abbott Vascular, Medtronic, and Boston Scientific. His co-authors reported relationships with Boston Scientific, Abbott Vascular, and Cordis. One of the authors is a full-time employee of Boston Scientific and two of the other authors are full-time employees and stock holders of Boston Scientific.

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